@article {23984,
	title = {The Age of NGC 6426, a Metal-poor Globular Cluster in the Galactic Halo},
	volume = {117},
	year = {1999},
	month = {1999/06/1},
	pages = {3059 - 3065},
	abstract = {We present B, V, R, and I photometry of the metal-poor globular cluster in the galactic halo, NGC 6426. The observations were performed using the 1.3 m Telescope at Skinakas Observatory in Crete. We derived the reddening of the cluster to be E(B-V)=0.39+/-0.02 [E(V-I)=0.53+/-0.03]. The metal abundance of the cluster was estimated from the shape of the red giant branch following the techniques by Sarajedini and by Da Costa \&amp; Armandroff. It was found to be [Fe/H]=-2.33+/-0.15 dex. The mean V magnitude of the RR Lyrae variables found in the cluster is 18.14+/-0.02 (based on a paper in preparation). The resulting distance modulus of the cluster is 16.41+/-0.07. Finally, we derived the relative age of NGC 6426. Using the methodology of Harris et al., we found that NGC 6426 is marginally older than M92 (by ~=0.7 Gyr). Following the Chaboyer, Demarque, \&amp; Sarajedini method we found NGC 6426 to have the same age as the mean metal-poor globular cluster of the galactic halo.},
	keywords = {GALAXY: GLOBULAR CLUSTERS: INDIVIDUAL: NGC NUMBER: NGC 6426, GALAXY: HALO},
	isbn = {0004-6256},
	url = {https://ui.adsabs.harvard.edu/abs/1999AJ....117.3059H},
	author = {Hatzidimitriou, D. and Papadakis, I. and Croke, B. F. W. and Papamastorakis, I. and Paleologou, E. V. and Xanthopoulos, E. and Haerendel, G.}
}
